1. Field of the Invention
The invention relates to a sail system in particular for ocean-going cargo ships, yachts, or the like.
2. Description of Related Art
From the media (see for example the article “Wie Tanker Kraftstoff sparen kann” [How tankers can save fuel] in the newspaper Welt am Sonntag, no. 5 of 3 Feb. 2008) people are familiar with calls for cruise ships and container ships to emit fewer pollutants in the future than they have up till now and for them to do their bit to save energy in the form of fossil fuels. Certain operators of vessels of this kind are having recourse to wind power as an additional means of propulsion and are making use of, for example, paragliders, airships or sails, which are able to assist the forward movement of the vessel and hence to make a contribution to the reduced emission of pollutants and to the saving of energy. Also, in the article “Betriebssimulation von Frachtschiffen mit Windzusatz-antrieb” [Simulation of the operation of wind-assisted cargo ships] by Clauss et al., 102. Hauptversammlung der Schiffbautechnischen Gesellschaft, 21 to 23.11.2007, Berlin, pages 1 to 11, there is a description of various types of sails which are compared with one another. There is mention here of what is referred to as a BSP sail which comprises modified flap profiles of the kind which are known from aeronautical engineering and jet engines. With the majority of such means of propulsion, some of which are new developments, it is difficult or even totally impossible to sail close to the wind and, this being the case, to sail close-hauled to more than an inadequate extent, or indeed at all. This means that the operators of such vessels have to keep very largely to historical seasonal sailing routes, and sometimes have to accept the need for considerable diversions. Diversions of this kind often negate the technical and environmental advantages of the additional means of propulsion.
Known from document DE 77 32 111 U1 is a sail system in which six expanses of sail arranged one behind the other are connected to a mast by means of an upper and a lower mounting which each extend horizontally. The expanses of sail are each able to rotate on an approximately vertical axis.
Known from GB 2 234 723 A is a sail system in which a mast which is U-shaped and hence of a goalpost-like form has an upper and a lower mounting. Between the mountings there are three expanses of sail which are able to be pivoted on approximately vertical rotating shafts which are fastened to the mountings.
Known from GB 742,128 A is a sailing device in which the upper ends of both expanses of sail, which ends taper to a point, are guided directly on the mast whereas the lower, forward, ends of the expanses of sail are adjustably guided in the longitudinal direction of the vessel on a mounting.